Cats reach sexual maturity, and can get pregnant, from around 4 months of age. Hence current advice is to have your cat neutered around 4 months old to prevent unwanted pregnancies. But what happens if we don’t neuter our female cats? What you may think of as a period for cats is often referred to as their ‘heat’ or ‘coming into season’ – scientifically it is known as oestrus. And it’s rather different from the process in primates (like humans).

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For female cats coming into season, or oestrus, isn’t one long period but many short periods (each cycle is about 14 days (about 2 weeks) long). Cats will continually come in and out of these short cycles in the hope of getting pregnant during the appropriate time of reproductive activity.

What are the signs?

During these cycles the cat will exhibit what could be described as ‘flirtatious’ behaviour!

This can include:

  • Lordosis – laying on their front half low, and raising their hindquarters, treading up and down with their hind feet, and moving their tail from side to side
  • Rubbing and rolling on the floor
  • Marking
  • Calling – a plaintive yet demanding rising and falling pitch

Cats reabsorb the lining of the uterus instead of bleeding it out so you will not see any blood during these times.

How does she fall pregnant?

Cats do not ovulate or release eggs into the fallopian tubes and into the horns of the uterus so that they can be fertilised until AFTER they have mated. Cats are “induced ovulators,”; this means that it is the act of mating that stimulates the release of luteinising hormone and ovulation. This contrasts with some other animals like humans and dogs, which already have the egg in situ when mating occurs.

What does this mean?

In order for an egg to become fertilised in cats, the egg must first be released via stimulation. The stimulus in cats is mating by a tomcat (male). It takes two days for the eggs to move down the fallopian tubes and reach the uterus and sperm survives for several days. As a consequence, the resultant litter may actually have several different fathers.

The eggs implant in the uterus and the resulting foetuses line up in two rows in the two horns of the uterus. If mating does not occur the eggs are not released. And the cycle (what you may call her period) is repeated again in these two weeks cycles.

So, the answer is that cats DO have an oestrus cycle. It just isn’t one that you may relate to as a typical ‘period’. 

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